Various devices are known and used for dispensing solid articles or tablets upon operation of an actuation means. However, such known dispensers have numerous drawbacks which make their use impractical for certain applications, such as reagent dispensers in automated clinical chemistry analyzers.
For example, since such automated analyzers are often left unattended, or the reagent dispensing takes place in an area where the operator cannot easily observe it, it is important that the dispenser reliably eject the exact number of tables (generally a single reagent tablet) every time it is activated. Otherwise, a false test result could be obtained. Furthermore, even if the analyzer is equipped to detect the fact that the reagent tablet has not been properly dispensed, this generally occurs downstream of the dispensing station and, due to the sequential nature of the automated instrument, it is not possible to bring the material being tested back to the dispensing station for the ejection of another tablet. Hence, the material, such as blood serum, entered into the analyzer for testing will be wasted.
Another problem encountered with the use of reagent tablets in clinical chemistry analyzers is that they are highly moisture-sensitive and, therefore, must be protected at all times from being exposed to even normal room humidity. Such exposure to ambient moisture will cause premature degradation of the reagent tablets, which may lead to inaccurate test readings. In addition, exposure to moisture may also cause the tablets to swell in size which may interfer with the reliable operation of the tablet dispenser.
Even if the dispenser storage area in the analyzer is dehumidified, in many instances it is still desirable to provide additional moisture protection for the tablets since they must generally be transported to and from the instrument in the dispenser and, even while stored in the instrument, it is possible for the dispenser to be exposed to high humidity levels associated with the operation of many such instruments in the event of equipment failure. This could be a particularly serious problem since such reagent tablets are relatively expensive and several thousand of them are likely to be stored in the analyzer at any given time.